Pole-number-changing rotary electric machines in which a number of poles is changed while driving in order to secure high torque and high output power over a wide range of rotational speeds are known as rotary electric machines to be used in electric vehicles, hybrid vehicles, and the like.
In one such conventional pole-number-changing rotary electric machine (see PTL 1, for example), three-phase coils are divided into two equal parts, and terminals are provided at ends of each coil except for a connecting portion, such that the coils having been divided into two equal parts form, for each phase, three phases and four poles. With PTL 1, in the case of two-pole drive, excitation coils in each slot are connected in series, and in the case of four-pole drive, connections of external coils of the excitation coils having been split into two equal parts are inverted and a power supply connection of the excitation coils of two phases is switched.
Further, in a separate conventional pole-number-changing rotary electric machine (see PTL 2, for example), six coils are arranged at 60-degree intervals, and mutually opposing coils are configured as a winding for one phase by being connected to each other so as to have the same polarity. With PTL 2, pole number changing of a rotary electric machine is performed by switching a phase sequence of a power supply voltage applied to three sets of three-phase windings configured in this way.